Household refuse consists mainly of packaging material; glass, paper, plastic and tin; food remnants; wastepaper; garden waste; and other waste such as broken lamps, empty batteries, broken toys and diverse other superfluous articles. Among other materials domestic waste comprises plastic, mainly PE, PP and PVC; organic material such as food remnants and garden waste; water present particularly in the organic material; paper, cardboard packaging, drink packs and old newspapers; metal such as tin and aluminium, but also for instance copper from appliances; glass such as broken glasses, jars and light bulbs; and textiles such as old clothing.
The following are often collected separately: paper and cardboard waste; glass waste; household hazardous waste (HHW or red waste); kitchen and garden waste (KGW or green waste); plastic bottles, metal and drink packaging (PMD or blue waste); textile waste; small appliances and electric household equipment (white goods), sound and vision electronics (brown goods) and ICT equipment (grey goods); and residual waste (grey waste), this being all other domestic waste. Paper and cardboard waste, glass waste, HHW, KGW, PMD, textile waste, and white, brown and grey goods can be wholly or partially recycled. Paper and cardboard waste and KGW are sometimes also incinerated. The residual waste (grey waste) can be incinerated or dumped. It can then for instance first be shredded, wherein waste bags are opened and the residual waste is reduced in size, after which for instance ferromagnetic materials are removed with a magnet and light plastic objects are blown out of the waste with air. The residual waste and KGW can for instance also be put together and composted.
The organic material can also be processed by digestion. For this purpose it must first be separated from the waste, household waste or residual waste. A suitable method herefor is pressing. The waste is fed here into a pressing chamber and compacted by means of a pressing member, for instance an auger or a plunger. At a sufficiently high pressure the cell walls break and the moisture enclosed in the cells is released. The consistency of the organic material hereby changes from more solid to more pasty and more liquid. Air, moisture and organic material leave the pressing chamber via discharge channels, gaps or perforations provided for the purpose. The remaining compacted material is removed from the pressing chamber by means of a method suitable for the purpose.
Described in NL7203727A is an example of pressing of organic material from waste with a plunger as pressing member, wherein the waste is fed by means of the same plunger into a pressing chamber and the remaining material is also removed again by means of this same plunger from the pressing chamber via a tube with an open outer end. The maximum pressing force is however limited here and the plunger always has to make a relatively large stroke. Found in EP0091365A1 is another example of pressing of organic material from waste with a first plunger as pressing member with which the waste is again also fed into a pressing chamber, and wherein the remaining material is now removed from the pressing chamber by means of a second plunger via a discharge opening provided for this purpose. Here too, the first plunger always has to make a relatively large stroke. The construction of the device, and in particular the relative placing of the components thereof, also limits the maximum pressing forces. U.S. Pat. No. 5,146,848A describes a pressing device for recovering liquid present in containers, comprising two plungers lying mutually in line and operating in mutually opposite directions. Both plungers have to be able here to supply the great force required for pressing out the relevant material, and this with a relatively large stroke, which makes the device costly and complex. U.S. Pat. No. 6,178,882B1 describes a device with the same function, though now with two plungers moving mutually perpendicularly of each other. The first plunger again compacts the relevant material and the waste is again fed with this first plunger into a pressing chamber while the compacted material is again removed from the pressing chamber by means of the second plunger. It is here also the case that the first plunger always has to make a relatively large stroke, and that the construction of the device, and particularly the relative placing of the components thereof, limits the maximum pressing forces.
Said known devices thus have in each case one or both of the following drawbacks: (1) the plunger which compacts the material, and so has to deliver great forces and therefore takes a heavy form, must make a relatively large stroke, this making the device costly and complex and limiting the processing speed, and (2) the construction of the device, and in particular the relative placing of the components thereof, limits the maximum pressing forces. It is more generally the case that known devices and methods for pressing organic material out of waste, household waste or residual waste, also have many other drawbacks in respect of effectiveness, efficiency and yield, robustness, durability, energy consumption, susceptibility to malfunction, wear, maintenance and the costs of production, exploitation and maintenance. The present invention now provides a solution which does not have the stated drawbacks, or at least does so to lesser extent.